JP2794849B2 - Electrophotographic photoreceptor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a photoconductor for electrophotography. Particularly, the present invention relates to an electrophotographic photoreceptor capable of converting an arbitrarily selected area into another substance and storing a pattern in this area.
More specifically, a pattern stored in an arbitrarily selected area on the photoconductor is converted into an electrostatic image using the memory effect of the photoconductor, and a simple image is formed using the electrostatic image. The present invention relates to an electrophotographic photoreceptor capable of performing repetitive printing in a process.

[Conventional technology]

In electrophotography, an image is selectively exposed to visible light on a part of the surface of a photoreceptor, only an unexposed area is used as a charged area, and a colorant (toner) is applied only to the charged area and developed. Colorant (toner) adhering only to charged area
Is transferred to an image holding medium such as paper, and a pattern represented by a selectively exposed area is embodied on the image holding medium such as paper.

The electrophotographic technology according to the prior art is largely classified into a technology using an electrostatic latent image (xerography method, Carlson method, etc.), a technology using a persistent internal polarization state, and a technology using a persistent conductive state. Separated.

 Each of them will be briefly described.

I. Technology that uses electrostatic latent images By using a selenium plate (selenium drum), etc., a series of steps of charging, image exposure (electrostatic latent image formation), development (colorant adhesion), transfer, and fixing are repeated. This is a technique for obtaining a copy. In this technique, one image exposure is required every time one copy is obtained.

B. Technology that uses a sustained internal polarization state When an image is exposed in a state where an electric field is applied to both sides of a plate composed of ZnS: CdS phosphor and anthracene, the carriers separated by this exposure cause the above-mentioned ZnS: CdS phosphor to be charged. Is trapped in a trap existing in a plate-like body composed of and anthracene, and an internal polarization is formed.The internal polarization has a property of being maintained even after the electric field / exposure is removed. Utilizing this technique, an internal polarization latent image is formed, the internal polarization latent image is developed, and the internal polarization latent image is transferred onto paper or the like to obtain a copy.

C. Technology that uses a persistent conductive state A photoconductor layer manufactured by dispersing an inorganic photoconductor powder such as zinc oxide and cadmium sulfide in a resin, and an organic photoconductor powder such as leucomalachite green are dispersed in the resin. Photoconductor layer, poly-N-vinylcarbazole (PV
K) -2,4,7-trinitrofluorenone (TNF) charge-transfer complex-based photoconductor with leucomalachite green (LM
G), a photoconductive layer prepared by adding a diazonium salt (DS) to a poly-N-vinylcarbazole (PVK) -2,4,7-trinitrofluorenone (TNF) charge transfer complex photoconductor. Layer produced by dispersing Cu · TCNQ complex in polymer formed on conductor layer, PVK · TeNF (2,4,5,7)
Irradiation of light or the like on a laminate of a photoconductive layer composed of a (tetranitrofluorenone) charge transfer complex photoconductor causes a difference in the conductive state between an exposed part and an unexposed part, and this conductive state Is persistent after the end of the exposure, and a conductive latent image is formed. Therefore, a technique for obtaining a copy by transferring this persistent conductive latent image to a paper or the like after development and transfer to a paper or the like It is.

By the way, an electrophotographic photoreceptor is a pattern transfer medium used in electrophotography, and a physical or chemical state difference occurs between an exposed area and an unexposed area when irradiated with light. In each of the above techniques (a), (b) and (c), a selenium plate (selenium drum)
Plates composed of ZnS: CdS phosphor and anthracenePVK
A photoconductive layer or the like made of a TeNF (2,4,5,7-tetranitrofluorenone) charge transfer complex photoconductor corresponds to a laminate of a switching layer and a carrier supply layer.

[Problems to be solved by the invention]

Of the three electrophotographic methods exemplified above, the xerographic method and the Carlson method are non-memory, as described above, and require one image exposure each time one copy is obtained. . The technology using the persistent internal polarization state and the technology using the continuous conductive state both use the memory of the photoreceptor. Therefore, each time a single copy is obtained, one image exposure is performed. Although they are not required, they are all in the technical development stage, have poor stability, cannot be said to have sufficiently high sensitivity and resolution, and have poor gradation (it is difficult to realize intermediate gradations, And either dark or colorless.) There is still room for improvement. Therefore, stability, sensitivity,
There has been a demand for an electrophotographic photoreceptor having good resolution gradation and storage performance.

SUMMARY OF THE INVENTION An object of the present invention is to meet this demand, and to provide an electrophotographic photosensitive member having good stability, sensitivity, resolution, and gradation, and having storage performance.

[Means for solving the problem]

The above object is achieved by forming a carrier generation layer (2) on a conductive substrate (3), and containing on the carrier generation layer (2) a compound which is converted into an insulator by irradiation of energy rays as a main component. Carrier transport layer (1)
Are formed to form a laminate, and an arbitrarily selected region on the surface of the carrier transport layer (1) is converted into an insulator (5) by irradiation with energy rays. Carrier transport layer (1) is polysilane and ± 0.15 eV based on the ionization potential of this polysilane
This is achieved by an electrophotographic photoreceptor comprising a composition with a low-molecular carrier transporting agent comprising a compound having an ionization potential within the range.

Polysilane which is one element of the composition constituting the carrier transport layer 1 constituting the electrophotographic photoreceptor according to the present invention is:
In general, polymers, especially homopolymers represented by the formula:
Includes copolymers or terpolymers.

However, in the formula, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , and R ₆ are selected from the group consisting of an alkyl group, an aryl group, a substituted alkyl group, a substituted aryl group, and an alkoxy group. , M, n, and p are numbers (mol%: hereinafter abbreviated as%) indicating the proportion of each monomer unit in the whole polymer composition, and the total of m + n + p is equal to 100%, and m, n, Alternatively, p can each be 0-100%. Each of the monomer units of the polysilane is randomly distributed throughout the polymer or is in a block shape with a variable amount. The weight average molecular weight of the polysilane is preferably 1,000
The upper limit is more preferably 2,000,000.

Examples of the alkyl group in the substituent represented by R in the above general formula include linear or branched alkyl groups having 1 to about 24 carbon atoms, preferably 1 to 8 carbon atoms. Branched alkyl groups, for example, methyl, ethyl, propyl, butyl, amyl, hexyl, octyl, nonyl, decyl, pentadecyl, stearyl, or unsaturated alkyls, including allyl groups And other similar substituted alkyl groups. Particularly preferred alkyl groups are a methyl group, an ethyl group, a propyl group, and a butyl group. Aryl substituents are those having 6 to about 24 carbon atoms and include phenyl, naphthyl,
And an anthryl group. These alkyl and aryl groups can be substituted with alkyl groups, aryl groups, halogen groups, nitro groups, amino groups, alkoxy groups, cyano groups, and other related substituents.

Examples of alkoxy groups are those having 1 to about 10 carbon atoms, such as methoxy, ethoxy, propoxy, butoxy, and other similar substituents.

Specific examples of the polysilane included in the above general formula include poly (methylphenyl) silane, poly (methylphenylsilylene-co-dimethyl) silane, poly (phenylethyl) silane, poly (p-tolylmethyl) silane, Polysilane having a phenyl group such as poly (diphenylsilylene-co-phenylmethyl) silane, poly (cyclohexylmethyl) silane, poly (tert-butylmethyl) silane, poly (n-propylmethyl) silane, poly (cyclotrimethylene) ) Silane, poly (cyclotetramethylene) silane, poly (cyclopentamethylene) silane, poly (di-t-butylsilylene-co-dimethyl) silane, poly (cyanoethylmethyl) silane, poly (2-
Examples include (acetoxyethylmethyl) silane and poly (2-carbomethoxyethylmethyl) silane, and polysilane having a phenyl group is particularly preferable.

These polysilanes can be synthesized by a known method (for example, RCWest, Comprehensive Organic Che
mistry, Vol. 2, Chapter 9.4, P. 365-387 (1982), edited
by G. Wilkinson et al., Pergamon Press, New York).

The low-molecular-weight carrier transporting agent which is the other component of the composition constituting the carrier transporting layer 1 constituting the electrophotographic photoreceptor according to the present invention has an ionization potential (hereinafter also referred to as Ip).
It is within ± 0.15 eV, preferably ± 0.08 eV, based on the ionization potential of polysilane which is another component of the composition together with the low-molecular carrier transporting agent. ± 0.15eV difference in ionization potential of low molecular carrier transporter for polysilane
If it is larger, the hole drift mobility of the carrier is reduced, the sensitivity is not sufficient, the resolution is reduced, and the gradation is deteriorated.

Specific examples of preferred low-molecular carrier transport agents include the following.

N, N, N ', N',-tetrakis (alkylphenyl)-
1,3-phenylenediamine (hereinafter also referred to as RPDA), particularly preferably N, N, N ', N',-tetrakis (3-methylphenyl) -1,3-phenylenediamine (hereinafter referred to as the following formula) Also called PDA.) In the present invention, among the low-molecular carrier transporting agents as described above, the difference in ionization potential with polysilane is ± 0.15.
Use a low-molecular carrier transport agent within eV. In the present invention, a polysilane having a phenyl group, which is a particularly preferred polysilane, such as poly (methylphenyl) silane (Ip
= 5.62 eV), PDA (Ip = 5.63 eV) or stilbene (Ip = 5.62 eV) is suitable.

The mixing ratio of the polysilane and the low-molecular carrier transport agent is as follows:
Based on the total amount of polysilane and low molecular weight carrier transporting agent, the low molecular weight carrier transporting agent is preferably from 1% by weight to 70% by weight.
%, More preferably 5% to 50% by weight, particularly preferably 40% to 50% by weight. If the compounding ratio is too small, the hole drift mobility does not greatly differ from the case where only polysilane is used, and improvement in sensitivity cannot be realized. On the other hand, if the compounding ratio is too large, the low-molecular carrier transporting agent crystallizes with time, appears as particles on the surface, does not form a good film, deteriorates sensitivity, and causes a reduction in resolution.

Carrier transport layer 1 of electrophotographic photoreceptor according to the present invention
Dissolves the above materials in a solvent such as benzene,
It can be formed by a known method such as a solvent coating method. Further, other methods such as a laminating method, a melt extrusion method, a dip coating method, and a spray method can be used.

The thickness of the carrier transport layer 7 of the electrophotographic photoreceptor according to the present invention is preferably 1 μm to 100 μm. In particular, 5 μm to 20
μm is preferred.

Various materials can be used as the material of the carrier generation layer 2 of the photoconductor for electrophotography according to the present invention.

First, as the material of the dye-based carrier generating layer, phthalocyanine dyes such as metal-free phthalocyanine, copper phthalocyanine, vanadyl phthalocyanine, titanyl phthalocyanine, azo dyes such as Sudan Red, Diane Red, Genus Green B, alcohol yellow, pyrenequinone , Indanthren Brilliant, Violet RR
P and other quinone dyes, quinocyanine dyes, indigo,
Examples include indigo dyes such as thioindigo, bisbenzimidazole dyes such as indofast orange, and quinacridone dyes.

These can be used by mixing with a resin binder such as polyester, polyvinyl butyral, polycarbonate, epoxy resin and polyhydroxy ether resin, if necessary.

Examples of the inorganic carrier generating layer material include amorphous selenium and selenium alloys such as diarsenic triselenide, trigonal selenium, amorphous silicon hydride, germanium, and silicon-germanium alloy. The thickness of the carrier generation layer 2 can be any thickness as long as the object of the present invention is achieved. Preferably, 0.1 μm to 5 μm
Is the thickness.

Examples of the material of the conductive substrate 3 include a conductive metal such as copper, aluminum, and gold, a glass provided with conductivity by attaching an ITO film or the like (eg, NESA glass), and a resin provided with conductivity. A film (eg, polyimide, polyester), paper with conductivity, or the like can be used.

The shape of the laminate of the carrier transport layer 1, the carrier generation layer 2, and the conductive substrate 3 can be any shape such as a sheet shape or a drum shape.

The function of the energy beam for changing the carrier transport layer 1 to an ecclematous body is to irradiate the carrier beam to generate a photochemical reaction to break the bond contained in the material constituting the carrier transport layer 1, or Since the purpose of the present invention is to realize crosslinking in the material constituting the transport layer 1, any energy ray having sufficient energy to realize this chemical reaction may be used. Specifically, an ultraviolet ray having a wavelength of 400 nm or less ( The preferred lower limit is 100 nm, and the more preferred lower limit is 300 nm.), Use of argon fluorine excimer laser light, synchrotron radiation light, particle beam such as X-ray, electron beam, ion beam, carbon dioxide laser light, etc. Can be done. As an economical method, ultraviolet rays from a mercury lamp are preferable, but for printing finer patterns, an electron beam or an excimer laser beam is preferable.

When the above-mentioned material constituting the carrier transport layer 1 is irradiated with the above-mentioned energy ray, a green layer is formed, and the thickness of the green layer can be changed according to the irradiation amount. Therefore, it is possible to exhibit gradation in the copied image.

Further, the amount of the energy beam irradiated to the carrier transport layer 1 depends on the kind and molecular weight of the material constituting the carrier transport layer 1, the thickness of the carrier transport layer 1, and the like. For example, in the case of poly (methylphenyl) silane having a weight average molecular weight of 5,000, assuming that the film thickness is 6 μm, assuming that a xenon lamp that generates ultraviolet light having a wavelength of 300 to 400 nm is used, 9.2 mW / cm ² By irradiating for about 22 minutes at an energy density of, the entire thickness of the irradiated area can be converted into an insulator. In other words, under the above conditions, the film thickness is 1 μm
The energy required to convert the material to an insulator is about 0.2 J / cm ² .

[Action]

The present invention provides a composition of polysilane and a low-molecular-weight carrier transporting agent having an ionization potential within 0.15 eV based on the ionization potential of the polysilane. It uses a newly discovered law of nature that the region that has been converted to an insulator leads to a long-term (permanent) loss of function as a carrier transport layer. More specifically, an arbitrarily selected region of the electrophotographic photoreceptor having the composition of the polysilane and the low-molecular carrier transporting agent as a carrier transporting layer is irradiated with an energy ray such as an ultraviolet ray. Only the region does not function as a normal carrier transport layer,
After negative charge is applied to the entire surface of the electrophotographic photoreceptor having a part of the region converted into an insulator in this way, when exposed to visible light, the unirradiated region functions as a normal carrier transport layer. However, although the charge is lost, the irradiated area does not function as a normal carrier transport layer, and negative charge remains only in this area. Therefore, a pattern represented by the charge remaining in this exposed area is used as a charged latent image. It is something that can be done. Therefore, with the selective insulation function realized by the irradiation of energy rays such as the ultraviolet rays described above, the desired pattern is permanently stored, and the electrophotographic photosensitive member that permanently stores the desired pattern is: A plurality of copies having the above-mentioned desired pattern can be formed by the steps of negative charge, exposure to the entire surface of visible light or the like, development (selective attachment of colorant), transfer and fixing.

Further, by performing reversal development of the related art such as applying a bias voltage, it is possible to easily reverse the copy to either a negative type or a positive type.

〔Example〕

Hereinafter, electrophotographic photoconductors according to two examples of the present invention will be described more specifically with reference to the drawings.

Example 1 See FIG. 1. On an aluminum substrate 3, titanyl phthalocyanine (TiOPc) was mixed with polyvinyl butyral (PVB) at a weight ratio of 1.
The composition dispersed in a ratio of 1 was applied to a thickness of 0.5 μm to form a carrier generation layer 2. Furthermore, using a method of West et al., Which uses methylphenyldichlorosilane as a raw material, a polysilane having a weight average molecular weight of 10,000 obtained by polymerization using sodium metal in toluene (Ip = 5.62 eV)
Is dissolved in benzene, and PDA (Ip = 5.63 eV) is added as a low-molecular carrier transporting agent at a concentration of 50% by weight based on the total amount of polysilane and PDA, and the bar coating method is used. After application, the carrier was dried to form a carrier transport layer 1 having a thickness of 6 μm, and an electrophotographic photoreceptor comprising a laminate of these three layers was manufactured. As a result of measuring the characteristics of the obtained electrophotographic photosensitive member (before exposure), the hole drift mobility was 10 ⁻³ cm ² / V · s.

See FIG. 2. An electrophotographic test chart 6 (pattern black, transparent base) is placed as a mask on the laminated photoreceptor thus manufactured, and ultraviolet rays 4 (wavelength: 300 to 400) are emitted by a mercury lamp.
nm) at an irradiation energy of 9.2 mW / cm ² for 60 minutes to perform image exposure, thereby converting the ultraviolet irradiation region to the insulator 5.

Next, printing was performed using a laser printer according to the related art, and this step will be described in detail.

Referring to FIG. 3, the entire upper surface of the carrier transport layer 3 was negatively charged using the corona charging device 8.

4 and 5, when the entire upper surface of the carrier transport layer 3 is exposed to visible light 7, positive charges are generated from the carrier generation layer 2 and move upward in the carrier generation layer 2. Then, the negative charge disappears in the ultraviolet non-irradiated region in combination with the negative charge. However, in the ultraviolet irradiation region, the above-mentioned positive charges are blocked by the insulating layer 5 and cannot be combined with the negative charges, so that the above-mentioned negative charges remain as they are.

Here, when a colorant such as a toner is sprayed on the carrier transport layer 3, the colorant such as the toner adheres only to the region where the negative charge remains (on the insulator layer 5) and is developed. Was.

Next, a color material 8 such as toner is transferred by placing an image holding medium such as paper on the carrier transport layer 3 in which the color material such as toner remains only on the developed ultraviolet irradiation area. This was fixed to make a copy.

In this way, a copy having a sharp negative image
Zero or more were created.

Further, when this negative image was subjected to reversal development, a clear positive image was obtained.

Example 2 The difference from Example 1 was that the weight average molecular weight of polysilane, which was the material of the carrier transport layer 1, was 5,000 (Ip = 5.62e).
Although only a certain point was given as V), almost the same results as in Example 1 were obtained.

Example 3 A photoconductor for electrophotography was produced in the same manner as in Example 1 except that the following azo compound was used as the carrier generation layer 2, but the same result as in Example 1 was obtained.

Example 4 A photoconductor for electrophotography was produced in the same manner as in Example 1 except that stilbene was used as the low-molecular carrier transporting agent.

Comparative Example 1 As a low-molecular carrier transport agent, the ionization potential was 5.38 eV.
Example 1 except that the following hydrazone derivative was used.
A photoconductor for electrophotography was produced in the same manner as described above, and the characteristics of the obtained photoconductor (before exposure) were measured. The hole drift mobility was greatly reduced to the order of 10 ⁻⁷ cm / V · s, and as a result of development, only an unclear negative type image was obtained.

〔The invention's effect〕

As described above, the electrophotographic photoreceptor according to the present invention includes a carrier generation layer formed on a conductive substrate, and a compound which is converted to an insulator by irradiation of energy rays on the carrier generation layer. Since a carrier transport layer composed of a layer containing as a layer is formed to form a laminated body, by irradiating only a partial area of the electrophotographic photoreceptor with an energy ray, the energy ray is irradiated. Only a part of the converted area can be converted to an insulator, and after only a part of the area is charged with a negative charge on the surface of the electrophotographic photosensitive member converted to the insulator, the entire surface is exposed with visible light. Then, the above-mentioned negative charges remain only in the energy-irradiated area and become an electrostatic latent image. Therefore, the electrophotographic photoreceptor of the present invention which has been partially exposed is used as a permanent print master. It can be. The electrophotographic photoreceptor according to the present invention is capable of additionally writing in an energy beam non-irradiated area. What is important in the electrophotographic photoreceptor according to the present invention is that the electrophotographic photoreceptor has excellent gradation and can be used for images having shading.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an electrophotographic photoconductor according to one embodiment of the present invention. FIG. 2 to FIG. 7 are explanatory diagrams of steps of printing using an electrophotographic photosensitive member according to one embodiment of the present invention. DESCRIPTION OF SYMBOLS 1 ... Carrier transport layer, 2 ... Carrier generating layer, 3 ... Conductive substrate, 4 ... Ultraviolet light, 5 ... Area converted to an insulator, 6 ... Electrophotographic test chart, 7 ... Visible Light 8 ... Colorant (toner) 9 ... Image support medium (paper).

Claims (1)

(57) [Claims] 1. A carrier generation layer (2) is formed on a conductive substrate (3), and the carrier generation layer (2) contains, as a main component, a compound which is converted into an insulator by irradiation with energy rays. A carrier transport layer (1) is formed to form a laminate, and a surface of the carrier transport layer (1), which is arbitrarily selected, is converted into an insulator (5) by irradiation with energy rays. In the electrophotographic photoreceptor, the carrier transport layer (1) comprises a composition of polysilane and a low-molecular carrier transport agent having an ionization potential within ± 0.15 eV based on the ionization potential of the polysilane. Photoconductor for electrophotography.